The double loop electrochemical potentiokinetic reactivation method was modified and applied to detect the susceptibility to intergranular corrosion of super austenitic stainless steel S32654 aged at 1000 °C. The precipitation behavior was clarified, and the corresponding intergranular corrosion mechanism of aged S32654 was proposed. The microstructure demonstrated that σ phase, Cr2N and π phase nucleated at the initial stages of aging and gradually grew larger with increasing aging time. The degree of sensitization increased rapidly in the early stage of aging and then showed a slow increasing rate during long term aging stage, and no self-healing has been observed. Such modified double loop electrochemical potentiokinetic reactivation method could successfully characterize the relationship between microstructure evolution and intergranular corrosion susceptibility of S32654. The mechanism of intergranular corrosion was attributed to the Cr and Mo depletion adjacent to σ phase and π phase and the Cr depletion around Cr2N. Display omitted •Precipitation behavior of S32654 at nose temperature (1000 °C) is investigated.•A modified DL-EPR method is established to detect IGC susceptibility of S32654.•The degree of sensitization increases with aging time and no self-healing occurs.•Cr-depleted zone and Mo-depleted zone are observed adjacent to the precipitates.•The IGC of S32654 is caused by the Cr- and Mo-depleted zones.